Automatic identification of field boundaries in a site-specific farming system

ABSTRACT

A farming system which identifies the boundaries of agricultural fields and performs functions based upon whether a vehicle is located within a particular field is disclosed. The system includes a location signal generation circuit which receives positioning signals and generates location signals representative of the location of the vehicle. The system further includes a memory circuit which stores geo-referenced digital maps of the fields and may include boundary data or application maps for each field. The system further includes a control circuit which compares the location signals to the data stored in the memory circuit to determine when the vehicle is located in a particular field. In one embodiment, the control circuit selects a variable-rate application map for the particular field and generates variable-rate control signals from the map data which are applied to a variable-rate applicator. In another embodiment, the control circuit stores characteristic data sensed by a sensing circuit with correlated location signals in a geo-referenced digital map for the particular field. In another embodiment, the control circuit generates height control signals to raise and lower an agricultural tool such as a tractor plow or a combine header based upon relationships between the location of the tool in a field and the location of attributes in the field such as field boundaries or obstructions.

FIELD OF THE INVENTION

The present invention relates to a system for performing a functionbased upon whether an agricultural vehicle is located within anagricultural field. In particular, the invention relates to a system forautomatically identifying when a vehicle is located within anagricultural field, and for performing a function when the vehicle islocated within the field.

BACKGROUND OF THE INVENTION

Research within the agricultural community has shown that management ofcrop production may be optimized by taking into account spatialvariations that often exist within a given farming field. For example,by varying the farming inputs applied to a field according to localconditions within the field, a farmer can optimize crop yield as afunction of the inputs being applied while preventing or minimizingenvironmental damage. This management technique has become known asprecision, site-specific, prescription or spatially-variable farming.

The management of a field using precision farming techniques requiresthe gathering and processing of data relating to site-specificcharacteristics of the field. Generally, site-specific input data isanalyzed in real-time or off-line to generate a prescription mapincluding desired application or control rates of a farming input. Acontrol system reads data from the prescription map and generates acontrol signal which is applied to a variable-rate controller forapplying a farming input to the field at a rate that varies as afunction of the location. Variable-rate controllers may be mounted onagricultural vehicles with attached variable-rate applicators, and maybe used to control application rates for applying seed, fertilizer,insecticide, herbicide or other inputs. The effect of the inputs may beanalyzed by gathering site-specific yield and moisture content data andcorrelating this data with the farming inputs, thereby allowing a userto optimize the amounts and combinations of farming inputs applied tothe field.

The spatially-variable characteristic data may be obtained by manualmeasuring, remote sensing, or sensing during field operations. Manualmeasurements typically involve taking a soil probe and analyzing thesoil in a laboratory to determine nutrient data or soil condition datasuch as soil type or soil classification. Taking manual measurements,however, is labor intensive and, due to high sampling costs, providesonly a limited number of data samples. Remote sensing may include takingaerial photographs or generating spectral images or maps from airborneor spaceborne multispectral sensors. Spectral data from remote sensing,however, is often difficult to correlate with a precise position in afield or with a specific quantifiable characteristic of the field. Bothmanual measurements and remote sensing require a user to conduct anairborne or ground-based survey of the field apart from normal fieldoperations.

Spatially-variable characteristic data may also be acquired duringnormal field operations using appropriate sensors supported by acombine, tractor or other vehicle. A variety of characteristics may besensed including soil properties (e.g., organic matter, fertility,nutrients, moisture content, compaction, topography or altitude), cropproperties (e.g., height, moisture content or yield), and farming inputsapplied to the field (e.g., fertilizers, herbicides, insecticides,seeds, cultural practices or tillage parameters and techniques used).Other spatially-variable characteristics may be manually sensed as afield is traversed (e.g., insect or weed infestation or landmarks). Asthese examples show, characteristics which correlate to a specificlocation include data related to local conditions of the field, farminginputs applied to the field, and crops harvested from the field.

Special problems exist, however, when site-specific farming equipment isused on more than one farm, or on multiple fields that are part of asingle farm. For example, because it is desirable to maintain farmingdata associated with each field independently of farming data associatedwith any other field, it would be desirable to have a site-specificfarming system capable of maintaining data from different fieldsindependently (e.g., using different files or layers of data). In such asystem, an operator of a vehicle may be required to manually select afield being worked from among various fields that have been defined inthe site-specific farming system. Requiring manual selection of aparticular field, however, increases the number of tasks that anoperator must perform. Also, manual selection may cause errors to occurin selecting a field being worked. Such errors may result in incorrectprescription maps being selected, or in received farming data beingstored in geo-referenced maps which do not correspond to the correctfield.

SUMMARY OF THE INVENTION

Accordingly, the present invention automatically determines when anagricultural vehicle is located within a particular field. Site-specificfarming data associated with any number of fields is provided in amemory circuit. The field boundaries may be defined in boundary dataassociated with each field, or may be determined using geo-referencedapplication maps associated with each field. Location signalsrepresentative of the location of the vehicle are compared to the fieldboundaries to determine if the vehicle is located without or within afield. Automatically identifying the field boundaries allows an operatorto work a field without being required to manually select the fieldbeing worked, decreasing the operator's workload and the possibility oferroneously selecting the field. The correct prescription map for thefield is selected automatically after the field is identified, or thecharacteristic data (e.g., yield) which is sensed is stored in thecorrect geo-referenced map of the field.

One embodiment of the present invention provides a system forcontrolling a variable-rate applicator coupled to an agriculturalvehicle. The applicator is configured to apply farming inputs to anagricultural field at a variable rate in response to variable-ratecontrol signals. The system includes a location signal generationcircuit configured to receive positioning signals and to generatelocation signals representative of the location of the vehicle, a memorycircuit configured with variable-rate application data including firstand second geo-referenced application maps representative of desiredamounts of farming inputs to apply to a first field and a second field,respectively, and a control circuit coupled to the location signalgeneration circuit, the memory circuit and the variable-rate applicator.The control circuit is configured to compare the location signals to thevariable-rate application data to determine whether the vehicle islocated within the first field or the second field, and to generate thevariable-rate control signals as a function of the location signalsbased upon the first geo-referenced application map when the vehicle islocated in the first field and based upon the second geo-referencedapplication map when the vehicle is located in the second field.

Another embodiment of the present invention provides a system forcontrolling a variable-rate applicator coupled to an agriculturalvehicle. The applicator is configured to apply farming inputs to anagricultural field at a variable rate in response to variable-ratecontrol signals. The system includes a location signal generationcircuit configured to receive positioning signals and to generatelocation signals representative of the location of the vehicle, a memorycircuit configured with boundary data representative of the boundariesof at least a first field and a second field, and with first and secondgeo-referenced variable-rate application data representative of desiredamounts of farming inputs to apply to the first field and the secondfield, respectively, and a control circuit coupled to the locationsignal generation circuit, the memory circuit and the variable-rateapplicator. The control circuit is configured to compare the locationsignals to the boundary data to determine whether the vehicle is locatedwithin the first field or the second field, and to generate thevariable-rate control signals as a function of the location signalsbased upon the first variable-rate application data when the vehicle islocated in the first field and based upon the second variable-rateapplication data when the vehicle is located in the second field.

Another embodiment of the present invention provides a system forsampling at least one characteristic of a field as a vehicle moves overthe field. The system includes a sensing circuit supported by thevehicle and configured to generate characteristic signals representativeof a characteristic sampled at a plurality of locations within thefield, a location signal generation circuit supported by the vehicle andconfigured to receive positioning signals and to generate locationsignals representative of the plurality of locations, a memory circuitconfigured with boundary data representative of the boundaries of atleast a first field and a second field, and a control circuit coupled tothe sensing circuit, the location signal generation circuit and thememory circuit. The control circuit is configured to compare thelocation signals to the boundary data to determine whether the vehicleis located within the first field or the second field, and to correlatethe characteristic signals with the location signals and to store thecorrelated characteristic and location signals in a first geo-referenceddigital map when the vehicle is located in the first field and in asecond geo-referenced digital map when the vehicle is located in thesecond field.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will become more fully understood from the followingdetailed description, taken in conjunction with the accompanyingdrawings, wherein like reference numerals refer to like parts, in which:

FIG. 1 is a block diagram illustrating a site-specific farming systemincluding vehicles equipped with sensors for sampling site-specificcharacteristics of a field and electronic displays for displayingvisible indicia of the characteristics in the vehicle cabs, and anoffice or portable computer;

FIG. 2 is a block diagram of the office or portable computer shown inFIG. 1 which can be used to process site-specific farming data;

FIG. 3 represents a layer of data representing a spatially-variablecharacteristic of a farming field stored in memory;

FIG. 4 shows a map of a farming field displayed on an electronic displayin a vehicle cab which includes visible indicia of a characteristic ofthe field;

FIG. 5 shows an exemplary map of a farm including a farmstead, roads,three fields (A, B and C), a lake, and a rock located in field C;

FIG. 6 represents three layers or geo-referenced maps which includeboundary data representative of the boundaries of each of the threefields (A, B and C) shown in FIG. 5;

FIG. 7 represents three geo-referenced prescription maps which includevariable-rate application data for each of the three fields (A, B and C)shown in FIG. 5; and

FIG. 8 is a block diagram illustrating a system for automaticallycontrolling the height of an agricultural tool based upon whether anagricultural vehicle is without or within a field.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring to FIG. 1, a site-specific farming system 100 includes one ormore core systems 102 which provide data processing functions fordifferent agricultural vehicles including tractors and combines. Infarming system 100, each tractor or combine is equipped with its owncore system 102. Each tractor is also equipped with an implement system104 appropriate for the task at hand, and core system 102 of the tractorcommunicates with implement system 104 over bus 106. Similarly, eachcombine is also equipped with a yield sensing system 108, and coresystem 102 of the combine communicates with yield sensing system 108over bus 110.

Preferably, core system 102 is removable and can be installed on avariety of agricultural vehicles. When installed on a tractor equippedwith implement system 104, core system 102 can be configured to operatein an "apply" mode wherein it collects, controls, records and displaysapplication rate data. The displayed data may include either the desiredapplication rate data (e.g., the prescription map) or the actualapplication rate data (e.g., the sensed feedback). When installed on acombine equipped with yield sensing system 108, core system 102 can beconfigured to operate in a "harvest" mode wherein it collects, recordsand displays harvest data (e.g., yield or moisture content). Core system102 may also operate in a "scout" mode wherein it records and displaysindicia (i.e., graphic symbols) representative of data observed andentered by an operator. Core system 102 may also provide directional orpositional assistance during scouting or when collecting soil samples.Sensing and control functions that require specialized input and outputprocessing are performed outside core system 102.

Farming system 100 also includes a workstation or personal computer 112which may be located in the farm office or may be portable. A medium ofcommunication is used to transfer site-specific data between core system102 and computer 112. Preferably, core system 102 and computer 112 eachinclude a read/write interface (not shown) for a removable memory card114 which can be transported between core system 102 and computer 112.Memory cards 114 may be Type II PCMCIA cards made by CentennialTechnologies, Inc. However, other mediums of communication (e.g., floppyor hard disk, RF, infrared, RS-232/485 links, etc.) may be used. Memorycard 114 is used to transfer site-specific characteristic data from coresystem 102 to computer 112, and to transfer prescription maps fromcomputer 112 to core system 102.

Core system 102 includes a digital data processing unit (DPU) 116 whichcommunicates with the vehicle operator through a user interface 118 vialinks 120 (e.g., an RS-232/485 interface; a standard keyboardinterface). DPU 116 includes a processor (e.g., a 486DX or Pentium®microprocessor) and various types of memory which may includenon-volatile memory (PROM, EEPROM or FLASH) and volatile memory (RAM).The processor executes a program stored in the non-volatile memory andthe volatile memory (RAM) may include a battery back-up circuit.Alternatively, DPU 116 may be implemented using dedicated, specificpurpose equipment or hard-wired logic circuitry. User interface 118includes a graphical user interface (GUI) 122 providing cursor control(e.g., a mouse, joystick or four-way switch with up, down, right andleft positions), assignable switches 124 (e.g., push buttons)configurable by the processor, a keyboard 125, and a voice-communicationinterface 126.

DPU 116 is configured to generate display signals which are applied to areconfigurable display 128 (e.g., a CRT, flat screen LCD display) viacommunication link 130. Display 128 is preferably an active-matrix LCDcapable of displaying full-motion video and a number of colors undervarying ambient light conditions. Display 128 is also capable ofdisplaying graphics and alpha-numeric characters. Display 128 is used,inter alia, to display the current configurations of assignable switches124. DPU 116, user interface 118 and display 128 are located in thevehicle cab such that the operator has easy access to user interface 118and an unobstructed or substantially unobstructed view of display 128.Core system 102 may also include a printer 132 in the cab whichcommunicates with DPU 116 via an interface 133 (e.g., an RS-232 link).

DPU 116 receives signals representing the speed of the vehicle fromground speed sensor 134 via interface 136 (e.g., a frequency interface).Ground speed sensor 134 may include a magnetic pickup sensor configuredto sense the speed of the vehicle's wheels or transmission, or mayinclude a radar device mounted to the body of the vehicle. The speedsignals may be used by DPU 116 to calculate distance travelled asdescribed below.

DPU 116 also communicates with a location signal generation circuit 138which generates location signals representing the vehicle's position.Circuit 138 includes a global positioning system (GPS) signal receiver140 with an associated antenna 142, and a differential GPS (DGPS) signalreceiver 144 with an associated antenna 146. A single antenna may beused in place of antennas 142 and 146. GPS receiver 140 may, forexample, be manufactured by Trimble Navigation Ltd. of California, andDGPS receiver 144 may be manufactured by Satloc, Inc. of Arizona. GPSreceiver 140 determines longitude and latitude coordinates (andaltitude) of the vehicle from signals transmitted by the GPS satellitenetwork. The accuracy of the position data is improved by applyingcorrection signals received by DGPS receiver 144. The differentialcorrection signals are used to correct errors present on GPS signalsincluding the selective availability error signal added to GPS signalsby the U.S. government. DGPS correction signals are transmitted by theU.S. Coast Guard and by commercial services. For example, the OmnistarDGPS system from John E. Chance & Assoc. of Texas includes a network often land-based differential reference stations which send correctionsignals to a master station which uploads signals to a satellite forbroadcast throughout North America. GPS differential correction signalsmay also be transmitted from a local base station such as the top of abuilding. In a preferred embodiment, DPU 116 interfaces with the SATLOCL-Band Integrated TerraStar DGPS System via an RS-485 communicationlink.

When core system 102 is mounted on a tractor, DPU 116 communicates withimplement system 104 via bus 106. Implement system 104 may include oneor more variable-rate controllers 148, variable-rate actuators 149 andapplication sensors 150. DPU 116 reads application rate data for aparticular field location from a prescription map (which may be suppliedby computer 112), or reads an input device such as a potentiometer (notshown) used to manually set a desired application rate, and generatescommands which are sent to variable-rate controllers 148. The commandoutput rate is a function of the speed of the tractor and the desiredapplication rate. For example, an increased speed will require anincreased output rate to maintain a constant desired application rate.In response, controllers 148 generate control signals which are appliedto variable-rate actuators 149. Application sensors 150 provide feedbacksignals representing the actual application rates to enable closed-loopcontrol. Variable-rate application systems include, for example, avariable-rate planter controller from Rawson Control Systems of Iowa anda variable-rate fertilizer spreader from Soil Teq., Inc. of Minnesota.Bus 106 may be an RS-485 bus for a single-channel variable-ratecontroller, or a J-1939 implement bus for a multiple-channel controller.

The tractor may also include site-specific sensors configured to sensecharacteristics of a field during field operations and communicate theinformation to DPU 116, even if the tractor is not equipped withvariable-rate controllers. For example, a tractor pulling a plow may beequipped with sensors for monitoring site-specific characteristics(e.g., draft force; implement position) as a field is worked. A tractorwith a hitch assembly control system with various sensors is describedin U.S. Pat. No. 5,421,416, commonly assigned and incorporated herein byreference. A tractor, as used herein, includes various agriculturalvehicles attached to implements such as planters, spreaders orfertilizers.

Desired application rate signals from a prescription map, actualapplication rate signals from feedback sensors 150, or signals fromanother site-specific sensor supported by the tractor may be processedby DPU 116 to form data representative of the respective characteristic.This characteristic data may be correlated with location datarepresentative of the location signals received from location signalgeneration circuit 138, and the correlated data stored in memory card114 or in another memory.

When core system 102 is mounted on a combine, DPU 116 communicates withyield sensing system 108 via link 110, which may carry RS-232/485signals. Yield sensing system 108 typically includes a yield flow sensor152 and a moisture sensor 154. Yield flow sensor 152 may include animpact-type mass flow rate sensor attached to a steel plate which isstruck by grain passing through the clean-grain elevator of the combineto measure the force of the grain flow. Moisture sensor 154 may be acapacitive-type sensor mounted on the underside of the grain tankloading auger of the combine to measure the moisture content of grainpassing near the sensor. Moisture sensor 154 may include a graintemperature sensor to compensate the grain moisture signals fortemperature. DPU 116 receives sensed signals from flow sensor 152 andmoisture sensor 154, and receives location signals from location signalgeneration circuit 138 which represent the positions of the combinewhere grain flow and moisture content were sampled. The grain flow andmoisture content signals are processed to form data representative ofthe respective characteristic, and this data is correlated with locationdata representative of the location signals. Correlated data is storedin memory card 114 or in another memory.

To convert the grain flow signals into yield data, the distancetravelled by the combine is determined by multiplying the combine'sspeed by elapsed time. The speed may be based upon signals sensed byspeed sensor 134, or may be determined by calculating the differencebetween successive position signals received from location signalgeneration circuit 138 and dividing by elapsed time. The yield (e.g.,bu/acre) is determined by dividing the quantity of sensed grain (e.g.,bu) by the area of the field harvested (e.g., acres), wherein thequantity of sensed grain is the product of the grain flow rate and time,and the area is the product of the width of cut and distance travelled.

In one embodiment, DPU 116 receives RS-485 serial communication signalsfrom a yield module unit (YMU) 155 which is configured to perform dataprocessing for yield sensing system 108. A separate YMU off-loads dataprocessing functions from DPU 116, and minimizes wiring between thecombine and the DPU. YMU 155 receives sensed signals from flow sensor152, moisture sensor 154, a header up/down sensor 156, an elevator speedsensor 158 and a ground speed sensor 160. Header up/down sensor 156senses the position of the combine's header to detect whether thecombine is harvesting. When header position is above a pre-programmedvalue, YMU 155 assumes the combine is not harvesting and yieldinformation is not calculated. A system for controlling and displayingthe status of a combine header is described in U.S. Pat. No. 5,465,560,commonly assigned and incorporated herein by reference. Elevator speedsensor 158 senses the speed of the clean grain elevator to determine thespeed at which grain passes through the elevator. Signals from sensor158 may be used to compensate the yield calculations for the delaybefore harvested grain is sensed. Ground speed sensor 160 senses groundspeed of the combine, and may be the same as ground speed sensor 134, orsimilar to it.

YMU 155 uses signals from sensors 152, 154, 156, 158 and 160 tocalculate and communicate yield and moisture content data to DPU 116 viabus 110. The update rate at which data is communicated may be once persecond. YMU 155 may provide instantaneous yield and moisture contentdata, and may also provide field and load total (summary) values forgrain weight, wet and dry bushels, average moisture, area harvested anddry yield. Thus, YMU 155 allows specific yield processing functions tobe moved from DPU 116. Alternatively, YMU 155 may send raw sensed datato DPU 116 and the DPU may perform the calculations. However, farmingsystem 100 could also be configured such that DPU 116 reads the signalsdirectly from the sensors.

Core system 102 may communicate with other vehicle systems over avehicle data bus (not shown). Preferably, the vehicle data bus conformsto the standards of SAE J-1939 ("Recommended Practice for a SerialControl and Communications Vehicle Network"). A bridge circuit may beused to facilitate the transfer of data between the vehicle data bus anda secondary implement bus coupled to implement system 104 and DPU 116.The bridge circuit may be used to filter data between busses, therebydecreasing bus loading.

Referring to FIG. 2, computer 112 is preferably a programmed personalcomputer including a processor 200, a memory circuit 202, a color ormonochrome display 204, input devices such as a keyboard 206 or a mouse208, and input/output interfaces such as a memory card interface 210, ahard or floppy disk drive interface 212, and other interfaces 214 (e.g.,RF or infrared). An input device such as a joystick, light pen or touchscreen may also be used. Alternatively, computer 112 may be implementedusing dedicated, specific-purpose equipment or hard-wired logiccircuitry. Processor 200 may be an x86 or Pentium® microprocessorconfigured to execute a program stored in memory 202 or on a disk readby disk drive interface 212. Preferably, processor 200 reads precisionfarming data including position information from memory card 114 usingmemory card interface 210. Data may also be entered using keyboard 206,mouse 208, disk drive interface 212, or another interface 214.

Processor 200 generates display signals which, when applied to display204, cause visual alpha-numeric and graphical indicia to be displayed.For example, the display signals may cause display 204 to create avisual map 216 of a field as well as icons 218 representing drawingtools in a toolbox. Preferably, display 204 is a color monitor, but itmay also be a monochrome monitor capable of displaying different lightintensity levels.

FIG. 3 generally represents the structure in which a layer ofsite-specific farming data representative of a characteristic of afarming field is stored in memory. The data structure may be referred toas a geo-referenced digital map, or a layer of data. The structure ispreferably implemented using a database 300 (e.g., a geographicalinformation system (GIS) database) represented by a table, wherein eachrow represents a characteristic data point taken at a location in thefield. For example, a layer having 5000 data points is represented by atable having 5000 rows. Columns of information are associated with eachdata point. For example, the columns shown in FIG. 3 include yield data(bu/acre), moisture content data, and the longitude and latitudecoordinates at which each data point was sampled. The data structure ofFIG. 3 represents, for example, a yield layer. Data in the first row(Data Point No. 1) indicates that flow sensor 152 and moisture sensor154 of the combine sensed grain flow corresponding to a yield of 32.0739bu/acre and a moisture content of 17.7, respectively, at a locationdefined by longitude and latitude coordinates -88.7291520 and39.0710720.

A similar structure may be used to store each layer of site-specificfarming data. For example, a pH layer may include a row for each datapoint and columns for pH, longitude and latitude. Thus, memory card 114may contain a layer of data for each site-specific characteristic of afield.

The data structure represented generally by FIG. 3 may includeadditional columns representing other spatially-variable data. Forexample, a harvest data structure may include the following fields:

    ______________________________________                                        Data Item    Description                                                      ______________________________________                                        Longitude    Longitude position of data from GPS                              Latitude     Latitude position of data from GPS                               Flow Rate    Weight (wet) of grain passing by flow                                         sensor 152 every second (e.g.,                                                lbs/sec)                                                         Moisture     Percent (%) of grain weight which is                                          moisture                                                         GPS Time     Time stamp from GPS (sec)                                        Cycles       Seconds covered by the data (e.g., 1,                                         2 or 3)                                                          Distance     Distance (inches) traveled since last                                         data point                                                       Swath        Width of cut of the header (inches)                              Header Pos   1 = header down; 0 = header up                                   Pass         Number of the pass through a field                               Grain        Type of grain (e.g., corn)                                       GPS Status   1 = good (>= 4 satellites); 2 =                                               marginal (3 satellites); 3 = bad (<=                                          2 satellites)                                                    Altitude     Altitude (feet) of data from GPS                                 ______________________________________                                    

The data structure may also include heading information such as avehicle identifier, a farm identifier, a field identifier, a loadidentifier, and a serial number for hardware components of farmingsystem 100 (e.g., a yield module serial number). A similar datastructure may be used to store application data. The harvest andapplication data structures are preferably stored as DOS files in memorycard 114.

DPU 116 and processor 200 use correlated characteristic and locationfarming data to perform various functions of site-specific farmingsystem 100. For example, DPU 116 or processor 200 use the correlatedfarming data to generate display signals which cause electronic display128 or 204, respectively, to plot a map of a field which includesvisible indicia of the characteristic data. DPU 116 typically plots themap in real-time as characteristic and location signals are receivedfrom the sensing circuits (e.g., flow sensor 152, moisture sensor 154,application sensors 150) and location signal generation circuit 138,respectively. However, DPU 116 may also plot a map off-line based uponfarming data previously stored in memory. For example, if a harvestoperation was stopped in mid-field on a previous day, DPU 116 maygenerate a yield map based on the previous day's yield data and continueplotting data on the yield map that is collected during the currentday's operation. In contrast, processor 200 typically plots the mapoff-line based upon farming data received from memory card 114.

FIG. 4 represents an exemplary display when core system 102 is mountedon a combine equipped with flow sensor 152 and moisture sensor 154, thecombine is harvesting grain, and DPU 116 is using the sensed data andcorrelated location data in real-time to plot a map of the field whichincludes visible indicia of the yield. A screen 400 of display 128includes a map display area 402 and a legend display area 403. In thisexample, the boundaries of the field being harvested are defined and arestored in memory. After entering a "harvest" mode of operation inresponse to actuation of one of assignable switches 124, DPU 116accesses the longitude and latitude coordinates of the field boundariesfrom memory and scales the field boundaries to correspond to a portionof map display area 402. DPU 116 scales the boundary data and producesdisplay signals which, when applied to display 128, generate a visiblemap 404 of the field boundaries within map display area 402.

At the start of the harvest, the combine was located at the upper-righthand corner of map 404. The combine then made a number of passes throughthe field, turning at the headlands (located at the boundaries of map404). The current location of the combine is marked by an icon 406, suchas an arrow which also indicates the direction of travel. The threecolumns of blocks indicate that the combine has made three passesthrough the field. Throughout the harvest, DPU 116 gathers site-specificdata sensed by flow sensor 152 and moisture sensor 154 and correlatesthe sensed data with the locations at which the sensed data was sampledusing signals from location signal generation circuit 138. The data maybe sampled, for example, at 1 second intervals. The correlated data isstored in memory (e.g., memory card 114) for later analysis by officecomputer 112. DPU 116 may be configured to not calculate yield databased upon an indication that the combine is not harvesting (e.g.,header position is above a threshold position). This indication may alsobe used to separate passes through the field.

To accurately correlate the location data with the sensed characteristicdata, DPU 116 is preferably programmed with variables, which may be setby the operator, which indicate the distance and direction between GPSantenna 142 and the sampled location of the field (i.e., between antenna142 and the combine's header or the tractor's implement). Thisinformation is used as an offset to correct the location data storedwith the sensed data. Also, to compensate for the time required forgrain entering the header of the combine to reach the flow sensor 152,DPU 116 is programmed with a delay value (e.g., 10 seconds). Sensed datais correlated with the location data received 10 seconds earlier. Thus,no data will be sensed and no data will be plotted until 10 secondsafter harvesting starts. In one embodiment, DPU 116 maintains a bufferof the last 20 positions received, and selects a position to use basedupon the delay value.

The characteristic data and correlated location data are used to producea display signal in real-time which, when applied to display 128,generates visible indicia of the characteristic data at correspondinglocations of map 404. DPU 116 gathers characteristic data over "square"areas of the field where the sides of the square are substantially equalto the width of cut of the combine (or the width of the implement).Other shapes or blocks could also be used such as rectangles where thewidth is equal to the width of cut and the length is equal to thedistance traversed in a predetermined time interval. Data within eachdata block is automatically processed or filtered (e.g., averaged)before being displayed. Averaging data as it is plotted eliminates theneed to plot every data point, thereby decreasing visual noise ondisplay 128. If desired, data representative of the blocks could bestored in memory rather than the raw data to reduce the memory storageand subsequent processing requirements. The average value of the data ineach data block, and location data associated with the data block(appropriately scaled), are used to produce the display signal appliedto display 128. In response, display 128 generates visible data blocks408 which include visible indicia of the average characteristic value atcorresponding locations of map 404.

Characteristic data may be visually represented on display 128 inseveral ways. In a preferred embodiment, distinguishable colorsrepresent different ranges of the average data in each visible datablock. For example, the colors red, orange, yellow, green, cyan, blueand violet may represent increasing ranges of average yield. Legend 410displays each color and its associated yield range: below 25 (red);25-49 (orange); 50-74 (yellow); 75-99 (green); 100-124 (cyan); 125-150(blue); and above 150 bu/acre of corn (violet). When a moisture map isdisplayed, the default colors and ranges are: 0-7% (red); 7-14%(orange); 14-21% (yellow); 21-28% (green); 29-35% (cyan); 35-42% (blue);and above 42% (violet). The ranges and colors could also be selectableby the user. The range represented by each color is represented bylegend 410 displayed within legend display area 403.

In one embodiment, the user selects an average value of thecharacteristic for the field and the ranges are based on the averagevalue, with green centered at the average. For example, each color mayrepresent a yield range of 5 bu/acre if the selected average yield is 50bu/acre or less, a range of 10 bu/acre if the selected average yield is50 to 125 bu/acre, or a range of 15 bu/acre if the selected averageyield is 125 bu/acre or more. In each case, the range limits are roundedto the next whole number (e.g., green=48-53 bu/acre for a selectedaverage yield of 50 bu/acre), and out of range values are displayedusing the appropriate end color (i.e., red or violet). Alternatively,ranges may be represented by alpha-numeric characters or by differentlight intensity levels or grey scales.

Once geo-referenced digital maps of a field have been stored in memory(e.g., memory card 114) as described above, DPU 116 or processor 200 mayread the correlated farming data from the memory and cause a map to beplotted off-line on display 128 or 204, respectively. The map includesrepresentations of the characteristic data. The map is generated in amanner similar to the manner in which DPU 116 generates a map inreal-time, except that the real-time position of the vehicle is notshown on the map, and the data may be plotted in any sequence and in anytime-frame.

The correlated farming data may also be used to perform functions suchas generating prescription maps or variable-rate application signals.For example, if the farming data indicates that areas of a field havevarying nutrient concentration levels, processor 200 could generate afertilizer prescription map which includes relatively high applicationrates for areas of the field with low nutrient levels and relatively lowapplication rates for areas of the field with high nutrient levels. Thisprescription map would balance the need to adequately fertilize thefield while minimizing the amount of fertilizer applied. Theprescription map could be provided to DPU 116 via memory card 114, andDPU 116 could generate commands based upon the map data and apply thecommands to variable-rate controllers 148.

Site-specific farming system 100 includes functions which facilitate useon more than one farm, or on a single farm having more than one field.These functions allow site-specific farming data associated with eachfield to be maintained independently of farming data associated with anyother field. These functions also simplify the tasks which are performedby the system operator.

Referring to FIG. 5, an exemplary farm 500 is used to explain thestructure and operation of site-specific farming system 100 in amultiple-field environment. Farm 500 includes a farmstead 502 withbuildings 504 and 506 and grain silos 508. Building 504 is a barn andbuilding 506 is a farmhouse including a farm office. A driveway 510connects building 504 with an east-west road 512, which intersects anorth-south road 514. Roads 512 and 514 divide farm 500 into quadrantscontaining a first field A, a second field B, a third field C and alake. Roads 512 and 514 provide access to fields A, B and C for anagricultural vehicle 516 garaged in barn 504. Access ways 518 provideaccess from the roads to the fields. Vehicle 516 may be, for example, atractor or a combine. A rock near or at the surface of field C isrepresented at reference numeral 520. Farming system 100 may, of course,be used on farms with different layouts.

Referring to FIG. 6, the boundaries of fields A, B and C are determinedand stored in geo-referenced boundary maps 600, 602 and 604,respectively. The maps are stored as separate layers or files in memorycard 114 or in another memory. The boundary data for the maps may bedetermined in several ways. For example, a map-drawing program may beexecuted on computer 112, and drawing tools 218 used to facilitate thecreation of the maps. For another example, a hardcopy map of farm 500may be digitized and stored in memory, or aerial photographs of the farmmay be registered to create digital maps. For another example, anagricultural vehicle equipped with farming system 100 may be drivenaround farm 500 in a scouting mode of operation while an operator entersvisual attributes of the farm (e.g., field boundaries, rocks, lakes,etc.) while the location signals received by location signal generationcircuit 138 are correlated with the visual attributes. Maps 600, 602 and604 include boundary data representative of the boundaries withcorrelated location data representative of the locations in therespective field at which the boundaries are located.

As agricultural vehicle 516 equipped with core system 102 is drivenabout farm 500, DPU 116 compares location signals generated by locationsignal generation circuit 138 to the boundaries of each field todetermine when the vehicle is located within a particular field and, ifso, which field the vehicle is located within. For example, assume thatmemory card 114 was programmed with boundary data representative of theboundaries of fields A, B and C and that vehicle 516 is driven from barn504 into field B. When vehicle 516 is still in barn 504, on driveway510, on road 512 and on access 518 leading to field B, comparisons ofthe location signals to the boundary data show that vehicle 516 is notwithin the boundaries of any field. However, as vehicle 516 enters fieldB, comparisons of the location signals to boundary map 602, whichrepresents the boundaries of field B, show that vehicle 516 has enteredfield B.

The operation of site-specific farming system 100 after entering a fielddepends upon the particular task being performed. For example, a tractorequipped with implement system 104 may start application of a farminginput at a variable-rate after identifying the field. Application datamay be determined by computer 112 and transferred to DPU 116 in the formof prescription maps stored in memory card 114. For example, referringto FIG. 7, prescription or variable-rate application data for fields A,B and C are stored in geo-referenced maps 700, 702 and 704,respectively. In one embodiment, each field was divided by computer 112into regions represented by grids on maps 700, 702 and 704. Anapplication rate is determined based upon other site-specific farmingdata and is stored in association with each region. Maps 700, 702 and704 include application rate data representative of desired applicationrates for a number of locations in the respective field correlated withlocation data representative of the locations at which the desired ratewill be applied. As vehicle 516 enters field B, DPU 116 selectsvariable-rate application map 702 since the vehicle is located withinfield B. The location signals are used to index the application ratesassociated with the locations in the field.

Application sensors 150 generate feedback signals representative of theactual amount of the farming input applied. The feedback signals may,for example, indicate the actual number of seeds being planted or theactual amount of fertilizer being applied. DPU 116 may use the feedbacksignals in the generation of the variable-rate control signals in aclosed-loop mode of operation. In addition, DPU 116 may store thefeedback signals and correlated location signals in a geo-referencedfeedback map associated with the particular field being worked. Thus,DPU 116 can produce geo-referenced digital maps representative of theactual amount of the farming input being applied which correspond to thecorrect field being worked.

Alternatively, separate boundary maps 600, 602 and 604 are not providedby memory card 114. Since the boundary data is not provided, DPU 116determines the boundaries of fields A, B and C using the location datastored in geo-referenced application maps 700, 702 and 704. The locationdata may, for example, be used to calculate boundary data equivalent tothe boundary data stored in maps 600, 602 and 604.

Another function which may be performed by site-specific farming system100 includes sampling of site-specific characteristic data. For example,vehicle 516 may be a combine equipped with a header for harvestinggrain. The combine supports flow sensor 152 and moisture content sensor154. When the combine leaves barn 504, comparisons of the locationsignals to the boundary data show that the combine is not within theboundaries of any field. However, as the combine enters field B,comparisons of the location signals to boundary map 602 show that thecombine has entered field B. DPU 116 stores sensed characteristic datasuch as yield and moisture content data and correlated location signalsin a geo-referenced digital map associated with field B. By comparingthe location signals to the boundary data and identifying the fieldbeing worked, DPU 116 insures that the sensed data is stored in thecorrect map. Thus, even if the combine were driven between fields A, Band C and used to harvest grain in each field, the resulting sensed datawill be stored in association with the correct field.

The comparison of the location signals to the boundaries of each field,or to boundary information within the geo-referenced application maps,allows DPU 116 to identify the farm and field in which the vehicle islocated. Thus, DPU 116 generates variable-rate control signals or storessensed characteristic data for the particular field being worked withoutrequiring the operator to manually select or identify the field.

The field boundary data can also be used to automatically control theheight or elevation of a tool as a vehicle repeatedly enters and exits afield at the borders or headlands of the field. Referring to FIG. 8, acontrol system 800 controls the height of an agricultural tool supportedby a vehicle. In this embodiment, control system 800 is a hitch assemblyor header assembly control system which includes an additional interfacefor receiving raise/lower information from core system 102.Alternatively, elements of core system 102 (e.g., location signalgeneration circuit 138; the interface for memory card 114) could beincluded in control system 800 and a separate core system 102 would notbe needed.

Control system 800 includes a control unit 802 which communicates withcore system 102 via link 804, which may be a discrete interface forcarrying discrete signals or a communication interface (e.g., RS-232)for carrying additional data (e.g., location data, boundary data).Control unit 802 receives vehicle speed signals directly from speedsensor 134 via link 806, or indirectly from core system 102. Controlunit 802 also receives raise and lower rate signals from a raise rateinput device 808 and a lower rate input device 810, respectively.Devices 808 and 810 are, for example, potentiometers.

Control unit 802 generates height control signals including a raisecontrol signal 812 applied to a raise coil 814 and a lower controlsignal 816 applied to a lower coil 818. Coils 814 and 818 are typicallysolenoids or relays, and control unit 802 may include apulse-width-modulated (PWM) interface to generate PWM raise and lowercontrol signals. Coils 814 and 818 control a valve assembly 820configured to selectively apply pressurized hydraulic fluid from a pump822 to a positioning assembly 824 via hydraulic fluid line 826.Positioning assembly 824 may include, for example, an hydrauliccylinder. Positioning assembly 824 raises an agricultural tool 826 inresponse to raise control signal 812 and lowers tool 826 in response tolower control signal 816. A height feedback sensor is coupled topositioning assembly 824 or tool 826 and is configured to generate aheight feedback signal representative of the height of tool 826. Thus,control unit 802 can control the height of tool 826 in a closed-loop.Other input signals, such as draft force and position command signals(not shown) are also inputs to control unit 802 and are used to set aposition command for tool 826.

In one embodiment, the vehicle is a tractor equipped with a hitchassembly control system, and tool 826 is an implement such as a plowwhich is raised and lowered by the hitch assembly. Further descriptionof a tractor having a hitch assembly control system is provided in U.S.Pat. No. 5,421,416, commonly assigned and herein incorporated byreference. In another embodiment, the vehicle is a combine equipped witha positioning assembly, and tool 826 is a header which is raised andlowered by the positioning assembly. Further description of a combineprovided with a header elevation control system is provided in U.S. Pat.No. 5,455,769, commonly assigned and herein incorporated by reference.

In operation, an operator typically actuates an input device such as amultiple-position switch to manually raise and lower tool 826 dependingupon the relationship between the location of a vehicle and theboundaries of one or more fields. These actuations, however, increasethe workload of the operator, and may result in tool 826 being raised orlowered too late or too early if the switch is manually actuated at thewrong time. To solve these problems, core system 102 transmitsraise/lower command signals to control unit 802 via link 804 dependentupon comparisons between the location signals and the boundary data. Forexample, if the vehicle is a tractor equipped with a plow, core system102 transmits a lower command signal when the location signals indicatethat the tractor has entered a field and transmits a raise commandsignal when the location signals indicate that the tractor has exitedthe field.

Control unit 802 receives the raise and lower command signals andgenerates raise signal 812 in response to a raise command from coresystem 102, and generates lower signal 816 in response to a lowercommand. Thus, in the above example, the hitch is lowered to a workingposition when the tractor enters a field and is raised to a transportposition when the tractor exits the field. The working position istypically set as a function of draft force or position command, and thetransport position is typically a position where the plow does not comeinto contact with the ground. If the boundary data represents theboundaries of more than one field, core system 102 generates the raiseand lower command signals based upon whether the vehicle is within orwithout any of the fields.

In one embodiment, control unit 802 reads the rate signals from rateinput devices 808 and 810 and generates height control signals 812 and816 to move tool 826 at a velocity dependent upon the rate signals. Inanother embodiment, lower control signal 816 is generated to move tool826 from a transport to a working height as a function of the locationsignals, boundary data and rate signals such that the tool reaches theworking height substantially when the vehicle reaches a field boundary.For example, control unit 802 may receive the location signals andboundary data from core system 102, and may estimate when the vehiclewill reach the field boundary from this information. The estimation mayaccount for vehicle speed determined by a time derivative of thelocation signals, and may also account for direction of the vehiclebased upon a vector between adjacent location signals. The estimatedtime to reach the field boundaries and the rate signals determine themagnitude and timing of lower control signal 816.

In yet another embodiment, control unit 802 also uses speed signals fromspeed sensor 134 to generate lower control signal 816. For example, ifthe distance between the vehicle and the boundaries and the vehiclespeed are known values, the time required for the vehicle to reach theboundary is equal to the distance divided by the speed. Height controlsignal 816 may be generated such that, at the velocity determined by therate signals, tool 826 reaches the working position when the vehiclereaches the boundaries.

Similarly, control system 800 can be used to raise and lower tool 826when a vehicle passes over a geographic attribute of a field. Forexample, control system 800 can raise a hitch when the vehicleapproaches an obstruction, such as rock 520 (FIG. 5), and lower thehitch after the vehicle passes over the rock. The location of theobstruction is defined in a geo-referenced obstruction map. This actionprotects a plow attached to the hitch from being damaged by the rock.

The location of rock 520 is stored in a geo-referenced map of field Cwithin memory circuit 114. The rock's location may be visually detectedand stored during a scouting operation or while the field is beingworked, or could be stored after the rock is hit by an implement such asa plow. Core system 102 transmits a raise command signal when thelocation signals indicate that the tractor is nearing rock 520 on acourse which will take the vehicle over the location of the rock.Control unit 802 receives the raise command signal and generates raisesignal 812 which, when applied to raise coil 814, causes the hitch toraise. The hitch is raised to a position which protects the plow frombeing damaged. This height may also be stored in the G.I.S. database.After the location signals indicate that the vehicle has passed overrock 520, core system 102 transmits a lower command signal. In response,control unit 802 generates lower signal 812 which, when applied to lowercoil 818, causes the hitch to lower. The hitch is lowered back down toits working position.

While the embodiments illustrated in the FIGURES and described above arepresently preferred, it should be understood that these embodiments areoffered by way of example only. The invention is not intended to belimited to any particular embodiment, but is intended to extend tovarious modifications that nevertheless fall within the scope of theappended claims.

What is claimed is:
 1. A system for controlling a variable-rateapplicator coupled to an agricultural vehicle, wherein the applicator isconfigured to apply farming inputs to an agricultural field at avariable rate in response to variable-rate control signals, the systemcomprising:a location signal generation circuit configured to receivepositioning signals and to generate location signals representative ofthe location of the vehicle; a memory circuit configured withvariable-rate application data including first and second geo-referencedapplication maps representative of desired amounts of farming inputs toapply to a first field and a second field, respectively; a controlcircuit coupled to the location signal generation circuit, the memorycircuit and the variable-rate applicator, the control circuit beingconfigured to compare the location signals to the variable-rateapplication data to determine whether the vehicle is located within thefirst field or the second field, and to generate the variable-ratecontrol signals as a function of the location signals based upon thefirst geo-referenced application map when the vehicle is located in thefirst field and based upon the second geo-referenced application mapwhen the vehicle is located in the second field; and an applicationsensor coupled to the control circuit and configured to detect theactual amount of farming inputs applied and to generate feedback signalsrepresentative thereof, the control circuit being configured to storethe feedback signals in first and second geo-referenced feedback mapswhen the vehicle is located in the first field and the second field,respectively.
 2. The system of claim 1, wherein the location signalgeneration circuit receives satellite-based global positioning system(GPS) signals and generates the location signals from the GPS signals.3. The system of claim 2, wherein the location signal generation circuitalso receives differential GPS (DGPS) signals and generates the locationsignals from the GPS and the DGPS signals.
 4. The system of claim 3,wherein the memory circuit includes a removable memory card.
 5. Thesystem of claim 1, wherein the control circuit is further configured togenerate the variable-rate control signals based upon the feedbacksignals.
 6. The system of claim 1, wherein the first and second fieldshave non-adjoining boundaries.
 7. A system for controlling avariable-rate applicator coupled to an agricultural vehicle, wherein theapplicator is configured to apply farming inputs to an agriculturalfield at a variable rate in response to variable-rate control signals,the system comprising:a location signal generation circuit configured toreceive positioning signals and to generate location signalsrepresentative of the location of the vehicle; a memory circuitconfigured with boundary data representative of the boundaries of atleast a first field and a second field, and with first and secondgeo-referenced variable-rate application data representative of desiredamounts of farming inputs to apply to the first field and the secondfield, respectively; and a control circuit coupled to the locationsignal generation circuit, the memory circuit and the variable-rateapplicator, the control circuit being configured to compare the locationsignals to the boundary data to determine whether the vehicle is locatedwithin the first field or the second field, and to generate thevariable-rate control signals as a function of the location signalsbased upon the first variable-rate application data when the vehicle islocated in the first field and based upon the second variable-rateapplication data when the vehicle is located in the second field.
 8. Thesystem of claim 7, wherein the location signal generation circuitreceives satellite-based global positioning system (GPS) signals andgenerates the location signals from the GPS signals.
 9. The system ofclaim 8, wherein the location signal generation circuit also receivesdifferential GPS (DGPS) signals and generates the location signals fromthe GPS and the DGPS signals.
 10. The system of claim 9, wherein thememory circuit includes a removable memory card.
 11. The system of claim7, further comprising an application sensor coupled to the controlcircuit and configured to detect the actual amount of farming inputsapplied and to generate feedback signals representative thereof, and thecontrol circuit is further configured to generate the variable-ratecontrol signals based upon the feedback signals.
 12. The system of claim11, wherein the control circuit is further configured to store thefeedback signals in first and second geo-referenced feedback maps whenthe vehicle is located in the first field and the second field,respectively.
 13. The system of claim 7, wherein the boundaries of thefirst and second fields are non-adjoining.
 14. A system for sampling atleast one characteristic of a field as a vehicle moves over the field,the system comprising:a sensing circuit supported by the vehicle andconfigured to generate characteristic signals representative of acharacteristic sampled at a plurality of locations within the field; alocation signal generation circuit supported by the vehicle andconfigured to receive positioning signals and to generate locationsignals representative of the plurality of locations; a memory circuitconfigured with boundary data representative of the boundaries of atleast a first field and a second field; and a control circuit coupled tothe sensing circuit, the location signal generation circuit and thememory circuit, the control circuit being configured to compare thelocation signals to the boundary data to determine whether the vehicleis located within the first field or the second field, and to correlatethe characteristic signals with the location signals and to store thecorrelated characteristic and location signals in a first geo-referenceddigital map when the vehicle is located in the first field and in asecond geo-referenced digital map when the vehicle is located in thesecond field.
 15. The system of claim 14, wherein the sensing circuitincludes a grain flow sensor.
 16. The system of claim 14, wherein thesensing circuit includes a moisture content sensor.
 17. The system ofclaim 14, wherein the location signal generation circuit receivessatellite-based global positioning system (GPS) signals and generatesthe location signals from the GPS signals.
 18. The system of claim 17,wherein the location signal generation circuit also receivesdifferential GPS (DGPS) signals and generates the location signals fromthe GPS and the DGPS signals.
 19. The system of claim 14, wherein thememory circuit includes a removable memory card.
 20. The system of claim14, wherein the boundaries of the first and second fields arenon-adjoining.